SLC-17 was built in 1956 by the
United States Air Force for use with the
PGM-17 Thor missile, the first operational
ballistic missile in the arsenal of the
United States. It was initially designed for testing suborbital launches of the Thor, in accordance to the
IRBM's planned stationing in the
United Kingdom as part of
Project Emily. Pad 17A supported its first Thor missile launch on 3 August 1957, and Pad 17B supported its first Thor launch on 25 January 1957. As the Thor got wound down from missile use due to the advent of longer-range
ICBMs, the site was upgraded in the early 1960s to support a variety of space-oriented launch vehicles derived from the basic Thor booster. Initially starting with the
Thor-Able in 1958, these Thor-based rockets came to be called the
Delta family of launch vehicles. Thirty-five early Delta rocket missions were launched from Complex 17 between the beginning of 1960 and the end of 1965. The Air Force transferred Launch Complex 17A to
NASA in 1965, but the site was returned to the military in 1988 to support
McDonnell Douglas's
Delta II program. As Delta II launches continued over the next decades, Pad 17B was modified in 1997 to support a new, more powerful launch vehicle, the
Delta III, which made its maiden flight from the complex on 26 August 1998. The launch ended in failure, as did a second launch the next year. After a third launch on 23 August 2000 placed a mass simulator into a lower than planned orbit, the program was abandoned. Among the major NASA missions launched from the complex were the
Explorer and
Pioneer space probes, all of the
Orbiting Solar Observatories, the
Solar Maximum Mission, biological satellites (
Biosatellite program), the
International Cometary Explorer (ICE), the
TIROS and
GOES meteorology satellites, and the
Mars Exploration Rovers
Spirit and
Opportunity. Following the last military launch, in August 2009, SLC-17A was withdrawn from use, and LC-17B was transferred to NASA for two remaining launches. On 10 September 2011, a Delta II 7920H-10C made the final launch from SLC-17B, carrying NASA's
GRAIL spacecraft. All remaining Delta II launches were made from
SLC-2W at
Vandenberg Air Force Base in
California until its ultimate retirement in 2018. At 11:00 UTC (7:00 a.m. EDT) on 12 July 2018, both launch towers had been demolished via controlled demolition to make way for
Moon Express to build and test its lunar lander. As of August 2024, the
United States Space Force (having taken over the Air Force's jurisdiction) plans to fully demolish SLC-17 and the neighboring
LC-18 in favor of extending Lighthouse Road and reconnecting its two separate sections back together. == Launch statistics ==